Web winder

ABSTRACT

A winder, e.g. for winding paper webs into rolls, comprises three winder drums forming first and second nips into which first and second mandrels are urged. Separate webs are fed to the two mandrels, one web being fed between a first and a second of the three drums and the other web being fed between the second and third drums. Various means may be employed for urging the mandrels towards the nips.

United States Patent Bennett et al.

[451 Apr. 25, 1972 WEB WINDER Inventors: John P. Bennett; Frank W. Wilshin, both of London, England Assignee: Masson Scott Thrissell Engineering Limited, London, England Filed: Apr. 2, 1970 Appl. No.: 25,204

Foreign Application Priority Data Apr. 3, 1969 Great Britain ..17,627/69 U.S. Cl ..242/66 Int. Cl .B65h 17/08 Field of Search ..242/64-66, 56, 242/562 [56] References Cited UNITED STATES PATENTS 3,383,064 5/1968 Daly et a1 ..242/56.2 3,450,364 6/1969 Marsh et a1 ..242/66 3,498,557 3/1970 Ball ..242/56 Primary Examiner-Leonard D. Christian Attorney-Craig, Antonelli and Hill [57] ABSTRACT A winder, e.g. for winding paper webs into rolls, comprises three winder drums forming first and second nips into which first and second mandrels are urged. Separate webs are fed to the two mandrels, one web being fed between a first and a second of the three drums and the other web being fed between the second and third drums. Various means may be employed for urging the mandrels towards the nips.

14 Claims, 13 Drawing Figures PATENTED APR 2 5 I972 SHEET 10F 5 @WW i526 Invenlors 1 :romv Pans: azmverr an FRANK WILLIAM WEI-SHIN y 4 7 Mf MAllor eys P'A'TE'N'TEBAPR 25 I972 3, 658,272

SHEET 3 BF 5 I I nvenlo s and F ANK wz'lAr/sm w syzu @414 M 4 Attorneys TMN PETER BENNETT PATENTED APR 2 5 I972 SHEET U 0F 5 Inventors Tow/v PETER (BENNETT Inn FRANK wluI'hM wxLsHzM B L 7 M11111. Ja y A llorneys PATENTEDAPR25 I972 3,658,272 SHEET 5 CF 5 I nvenlors nun PETER BEND/El! Md RA/Vk WILLIAM wLLsnrN m4 J/ZL Attorneys WEB WINDER The present invention relates to winders and more particularly to winders for winding webs of paper into rolls.

In one prior art arrangement of a winder two winder drums are employed each of which rotates about a horizontal axis, the two drums being located side by side so that a mandrel or core can rest in the nip between them and be rotated by the winder drums to cause a web of paper initially connected to the mandrel or core to be wound onto the mandrel or core. With such as arrangement the two winder drums also act as the support for the roll of paper being built up and because of this fact this arrangement has the disadvantage that the heavier the roll gets the tighter the paper is wound thus making it very difficult to control the tightness of the paper throughout the rollf In another prior art arrangement (e.g. U.S. Pat. No. 2,355,318 Moravek or U.S. Pat. No. 3,383,064 Daly) the above mentioned problem is dealt'with by mounting the two winder drums one above the other and providing a separate support for the mandrel. In this arrangement because the weight ofthe paper is no longer relied upon to hold the roll against the nip of the two winder drums some means is also provided for urging the mandrel into the nip between the two winder drums. However, with such an arrangement there is the disadvantage that, when it is required to wind two rolls from a split web it is not possible to feed the two split webs to their associated mandrels, one on either side of the pair of winder drums, so that each split web travels between a pair of winder drums before engaging the associated mandrel. This results in the two wound rolls having different characteristics.

The present invention is concerned with providing a winder which will overcome the last mentioned difficulty by ensuring that the paths traversed by the two split webs are substantially the same and are subjected to substantially the same forces.

According to the present invention there is provided a winder which has at least three winder drums forming first and second nips into which first and second mandrels are adapted to be urged, the disposition of the three winder drums with respect to one another being such that the split web can be threaded with respect to the winder drums in such a way that a first width of the split web can be fed to the first mandrel between a first and second of the three winder drums and a second width of split web can be fed to the second mandrel between the second and third drums of the three winder drums, there being supports for the two mandrels to enable them to move away from and towards the two nips and means to urge the two mandrels towards their respective nips.

Preferably the first and third winder drums are pivotal away from the mandrel after the roll of paper has been wound to a predetermined diameter so that thereafter each of the two rolls then only bears against the second winder drum.

The second winder drum may have a larger diameter than the first and third winder drums. Conveniently the three winder drums are substantially in line with one another, the line being inclined to the horizontal; in one preferred arrangement the three winder drums are in a substantially vertical disposition with respect to one another. Alternatively, however, the three winder drums may be disposed in a triangular configuration.

Each of said mandrels may be mounted on a carriage which is movable along a track (e.g. slidable along rails) towards and away from the nip between a pair of the three winder drums, the carriage being drivingly connected to means (e.g. a hydraulic ram mounted on a fixed support) for urging the carriage towards the said nip between the two winder drums.

The means to urge the carriage towards the said nip may comprise a pivotal arm which has one end connected to a fixed pivot and the other end connected directly or indirectly to the carriage, the arm being movable about the said pivoted end by a ram. Said carriage may carry a first toothed member which meshes with a second toothed member carried'by a fixed support, the two toothed members being movable with respect to one another to cause said carriage to be driven towards or away from the nip between the two winder drums. In such an arrangement, one of the members may comprise a toothed rack and the other member comprise a pinion which is rotatable by a motor to cause relative longitudinal movement between the pinion and the rack. In an alternative form,

a the carriage is formed with a first toothed rack and a second toothed rack is secured to a fixed support, a pinion being located between the two racks and meshing with both ofthem so that movement of the pinion along the fixed second rack a given amount L will cause longitudinal movement equal to 2L of the first rack. In this latter form, the pinion is conveniently mounted on the end ofa hydraulic ram so that it can be moved along the second fixed rack, by energisation of said ram.

In yet another variant the carriage carries a motor which is connected to drive a gear which meshes with a fixed toothed rack mounted on a fixed support so that energisation of the motor causes the carriage to be moved towards oraway from the nip between the pair of winder drums. If preferred, however, the carriage may carry a toothed rack which is engageable in turn by each of a plurality of driven gears located along the track so that the toothed rack and hence the carriage can be driven from each gear to the next adjacent gear in succession to move the carriage either towards or away from the nip between the two winder drums. Yet again, the carriage may be connected to driving means comprising an endless bend to one run of which the carriage is secured, so that movement of the endless band in one direction or the other causes the carriage to move towards or away from the nip between the two winder drums.

To give a better understanding of the invention various preferred embodiments thereof will now be described, by way of example only, with reference to the accompanying drawings, in which:

FIG. 1 is a diagrammatic representation of a first form of winder embodying the invention;

FIG. 2 is a diagrammatic representation of a second form of winder embodying the invention;

FIG. 3 is a fragmentary enlarged view of part of the winder of FIG. 2;

FIG. 4 is a diagrammatic representation of a prior art winder;

FIG. 5 is a diagrammatic representation of part of the winder of FIG. 1;

FIGS. 6 to 12 show diagrammatically various arrangements for supporting the mandrels shown in the embodiments of FIGS. 1,2 and 3.

FIG. 1

A roll of paper 1 which is to be rewound is carried on a stand 2, the winder, constructed according to the present invention, for rewinding this roll being generally indicated by the reference numeral 3.

The winder 3 comprises essentially three winder drums 4, 5 and 6, which in this embodiment, lie substantially in a vertical line with respect to one another.

A first track 7 leads into the nip between the winder drums 4 and 5 and a second track 8 leads into the nip between the winder drums 5 and 6. A first carriage 9 is movable along the track 7 and a second carriage 10 is movable along the track 8, the first carriage 9 being adapted to carry a first mandrel or core 11 and the second carriage 10 being adapted to carry a second mandrel or core 12.

Associated with each of the carriages 9 and 10 are means to urge the respective carriage towards the respective nip but being retractable as the diameter of the roll being wound on the mandrel increases. Various embodiments of the said means are shown in more detail in FIGS. 6 to 12 and are described later.

After leaving the roll 1 the web of paper passes around idler rollers 13 and then between slitter knives 14 which serve to cut the web into, in this case, two webs of narrower width, la and lb-respectively. The slitter knives 14 may be of any conventional form.

Both the split webs 1a and 1b then pass between the two winder drums 4 and 5, the web 1a then being engaged on the first mandrel 11. The web lb also passes around the winder drum and then between the winder drums 5 and 6 to be engaged on the second mandrel 12. Thus both the split webs 1a and 1b pass at least once between a pair of the winder drums and approach the associated mandrel from between a pair of winder drums. This is in contrast with known winders employing only two winder drums positioned vertically with respect to one another where only one of the split webs, in the case of there being only two, can pass between the winder drums and approach the respective mandrel after having done so.

FIG. 4 illustrates diagrammatically a two drum winder of the kind disclosed in the aforementioned patents.

In such a winder two mandrels 11,12 are again provided and one of the split webs 1b is tensioned around the inner or minor part .r of the circumference of the mandrel 12 by the nips formed by the mandrel 12 with two winder drums 45 and 46, the drum 46 having a higher peripheral speed than the drum 45. By contrast, the split web 1a is tensioned around the outer or major part yof the circumference of the mandrel 11. This difference in the distance over which the split webs are stretched can give rise to differences in the characteristics of the two reels wound from the split webs 1a and lb. With a twodrum arrangement of this known kind it is not possible to thread the split webs in such a way that both of them are tensioned over the distance .r or the distance y, i.e. one will always be over the distance .r and the other over the distance y.

However, with the three drum arrangement of FIG. 1, embodying the present invention, part of which is illustrated on a larger scale in FIG. 5, it is possible to thread the split webs so that they both (or all where there are more than two) are tensioned over the same distances, i.e. they can both be or v feeds. Thus reels wound on a winder constructed according to the present invention are more likely to have consistent characteristics. The winder drums 4 and 6 would have a higher peripheral speed than the drum 5 and this could be effected by using the arrangement disclosed in US Pat. No. 3,450,364 dated June 17, 1969.

As the webs la and lb build up on the mandrels l1 and 12 respectively the mandrels are forced away from the respective nips between the winder drums in the directions of the arrows A and B respectively; this movement is however resisted by a reaction force provided by the means referred to earlier and examples of which are shown in FIGS. 6 to 12 following. This reaction means can be accurately controlled so that the tension of the web built up in the respective reels can also be accurately controlled.

To obtain the necessary tightness at the centre of the reel the reel is wound initially in contact with both winder drums, i.e. drums 4,5 or drums 5, 6. However, when the reel has built up to a predetermined diameter the necessary tightness can then be achieved by winding the reel on only one drum, i.e. drum 5. In this embodiment this is achieved by swinging the drums 4 and 6 (which may be mounted, for example, as explained below with reference to FIGS. 2 and 3) out of contact with the two reels to leave the two reels in contact only with the centre drum 5.

FIGS. 2 AND 3 In this embodiment parts corresponding to parts in FIG. 1 have been marked with the same reference numerals. In this embodiment the three winder drums 4, 5 and 6 are situated in a different orientation, being again substantially in line but the line being at a substantial angle to the vertical.

Apart from this different orientation of the winder drums the two winder drums 4 and 6 are of substantially smaller diameter than the winder drum 5 and are mounted on arms 37 and 44 which have pivots coaxial with the drum 5 so that they can be rotated as indicated by the arrow C to bring either of the winder drums 4 and 6 into or out of engagement with the mandrels, or the web wound on them, so that each of the mandrels can either coact with a pair of winder drums 4, 5 or 5,6 or can coact solely with the winder drum 5. (A single arm or frame may be used in place of the two arms 37, 44).

Instead of being mounted on carriages which are movable along tracks, the mandrels 11 and 12 are carried by the free ends of two pairs of arms 38 and 39 respectively which are pivotal about fixed mountings 40 and 41 respectively to allow the mandrels 11 and 12 to be moved in arcs towards or away from the drums 4, 5 or 5, 6 respectively and to allow the wound reels to be lowered on to a trolley, stand or the floor. The movement of the arms 38 and 39 is controlled by hydraulic rams 42 and 43 respectively. The rams 42, 43 and mountings 40, 41 are carried on tables 47, each slidable transversely ofthe machine on rails 48.

Because the drums 4, 5 and 6 are mounted on the arms 37 and 44 they can be positioned so that the reels are kept in contact with both drums 4, 5 or 5, 6 (see FIG. 3 broken lines), until the reels have built up to the predetermined diameter referred to earlier, at which point the drums 4 and 6 can be swung out of contact (see FIG. 3, solid lines).

An automatic control system (not shown) could be arranged to swing the winder drums 4 and 6 out of contact with the two reels after the two reels had built up to a predetermined diameter so that thereafter the two reels would then subsequently be built-up only on the winder drum 5, for the reasons discussed earlier.

Although only two configurations for the three winder drums 4, 5 and 6 have been illustrated other configurations could be employed; for example, the three winder drums 4, 5 and 6 could be in a substantially triangular configuration with respect to each other. With the latter configuration, the advantage can still be obtained that, as opposed to a two drum arrangement, the split webs can be introduced to their associated mandrel by being passed between a pair of winder drums to give the two or two yfeeds referred to earlier.

The drums 4,5 and 6 in both embodiments described above preferably have a helical groove formed in their surfaces to allow the escape of air trapped by the paper and to effect spreading of the paper outwardly from the mid-point of the drums.

The two parallel tracks 7 or 8 (FIG. 1) and arms 38, 39 (FIG. 2) are adjustable with respect to one another to vary the width of reel which they can accommodate. Said tracks 7, 8 are carried on supporting members 7a, 8a respectively and these supporting members are slidable on transverse supporting surfaces 7b, 8b. Movement of the members 70, on surfaces 7b, 8b may be produced by any convenient drive means (not shown), e.g. hydraulic rams or lead screws. The arrangement also permits movement of the tracks 7, 8 and members 7a, 8a transversely of the machine without altering their separation, so as to change the lateral position of the reel being formed relative to the rest ofthe apparatus.

The arms 38, 39 (FIG. 2) are movable transversely of the machine in a similar manner, the tables 47 sliding on the rails 48 when such movements are made. The arms 38 and 39 (FIGS. 2 and 3) are similarly adjustable.

Various arrangements for providing the above mentioned reaction force will now be described with reference to FIGS. 6 to 12 all of which are fragmentary views on an enlarged scale of the second carriage 10 and its associated track 8 FIG. 6

The carriage 10 has a link 15 pivotally connected to it at one end of the link, the other end ofthe link 15 being pivotally connected to an arm 16. The similar link 15 and arm 16 is also mounted on the other side of the carriage (not shown) the two arms 16 being thus located one on each side of the track 8. The lower ends of the arms 16 are mounted on a transverse shaft 16 which is rotatable in bearings 18 so that the arms 16 can move in the are indicated by the double ended arrow in FIG. 3. The links 15 serve to take up the difference between the arcuate movement of the outer ends of the arms 16 and the linear movement of the carriage 10 along the track 8.

Movement of the carriage 10 in the direction of the arrow B is resisted by a hydraulic ram, or rams 19, acting on the arm, or arms 16. The hydraulic ram, or rams 19, thus provide the reaction force which holds the roll against the winder drum or drums.

A supporting table 49 is slidable transversely of the machine on rails 49A, permitting transverse positioning of the track 8 as desired, as in the embodiment of FIG. 1.

In this embodiment the track 8 slopes downwardly away from the winder drums 5 and 6. A similar arrangement to that shown in FIG. 6 would be employed in respect of the carriage 9 and track 7.

The above described mechanism could be modified to make the link lockable with respect to the arm 16 when the carriage is at the lower end of the track 8 so that further pivotal movement of the arm 16 in the direction of the arrow B will lift the carriage off the track 8. The arm can then be further pivoted to deposit the roll on a trolley, a stand or the floor.

In a further modification the link 15 could be dispensed with and the arm 16 could act directly on the carriage 10. There would then be sliding movement of the contact surfaces of the carriage 10 and arm 16 to compensate for the arcuate movement of the arm compared with the linear movement of the carriage 10.

FIG. 6A

The arrangement shown in this figure is a modification of that shown in FIG. 6, providing for tilting of the track 8 so that winding may be effected with the reel being formed in contact with two drums 5, 6 (as when winding starts, with the mandrel at position 12a) or in contact with the drum 5 only, as indicated by the full line showing of the reel being wound on mandrel 12 and of the track 8. The large circle in broken line indicates the size of a completed reel, the mandrel at completion ofwinding being at position 12b.

As shown in FIG. 6A, the track 8 is carried at the top of a frame 50, mounted on a pivot 51. The pivot 51 is at one end of a mounting table 52, and at the other end of said table there is provided a pivot 53 for a hydraulic jack 54; said jack has its other end connected to the frame 50 by a pivot 55. It will be clear that the jack 54 may be operated to tilt the frame 50, and hence the track 8, to any desired angle. The range of movement of the frame 50 is preferably large enough to be useful in unloading completed reels, the frame 50 being tilted counterclockwise to lower the reel e.g. on to a trolley (not shown).

To avoid unwanted movement of the arm 16 relative to the track 8 when the angle ofthe latter changes, the arm 16 has its lower pivot at the point 55, and the hydraulic jack 19, while still connected to the arm 16 as in FIG. 6, has its other end pivotally connected to the frame 50 as indicated at 56.

The table 52 is carried on two supporting rails 57, which permit transverse movement of said table and of all the parts carried by it, corresponding to the movement of members 7a, 8a on surfaces 7b, 8b (FIG. 1).

FIG. 7

In this embodiment the carriage 10 is provided with a first toothed rack 20 which is engageable by a pinion 21 carried on the end of an arm 22 connected to a hydraulic ram 23. The pinion 21 also meshes with a second fixed rack 24 so that for every increment of movement of the pinion 21 along the direction of the track 8 with respect to the second fixed rack 24 there is twice the movement of the first rack 20 and thus the carriage 10 along the track 8. The ram 23 provides the reaction force against movement of the carriage 10 away from the winder drums 5 and 6. Again, as with the arrangement of FIG. 4, the track 8 slopes downwardly away from the winder drums 5 and 6 and this is also the case with the following arrangements described with reference to FIGS. 6 to 9.

FIG. 8

In this arrangement the carriage 10 carries a hydraulic motor 25 which drives a pinion 26 which in turn is in mesh with a fixed toothed rack 27 so that the motor 25 providesthe necessary resistance against movement of the carriage 10 Thus, as the carriage 10 tends to move along the track 8 in the direction of the arrow B its movement is resisted by the motor 31 through the pinions 29 and transfer gearing 30 thus maintaining the roll at the desired pressure against the winder drums 5 and 6 or against the winder drum 5 by itself.

FIG. 10

In this embodiment the carriage 10 is connected by a rod 32 to a hydraulic ram 33 which provides the necessary reaction against movement of the carriage 10 in the direction of the arrow B.

FIG. 11

In this embodiment the carriage 10 is connected to an endless band 34 which is drivably connected by a driving pulley 35 to a hydraulic motor 36 to provide the necessary reaction against movement of the carriage 10 along the track 8 in the direction of the arrow B.

In all the embodiments of FIGS. 7 to 11 the track 8, and associated mechanism, may be pivotally mounted e.g. may be on a mounting similar to the frame 50 (FIG. 6A) to permit winding to be effected by engagement between the reel and the drum 5 only when required and to assist in unloading completed reels.

FIG. 12

In this embodiment a similar arrangement to that of FIG. 6 is employed, like reference numerals being used to denote like parts. However, in this embodiment the track 8 is fore-shortened, compared with that of FIG. 6. In operation the initial part of each reel is wound with the carriage l0 resting on the track 8 and with the reel in contact with both drums 4 and 5, but when a predetermined diameter is reached (less than the effective length of the track 8) the link 15 is locked so that further arcuate movement of the arms 16 results in the reel following the arcuate path indicated. Thus, the reel on the mandrel 12 will then move out of contact with the drum 6 and continue to be wound only on the drum 5. In the case of the reel on the mandrel 11, the drum 4 is swung out of contact with the reel, as indicated in broken lines, to allow the reel to follow the arcuate path indicated, the reel then being wound only on the centre drum 5.

In all the embodiments of the invention which have been described, the mandrels may each extend through the whole length of the paper roll being wound and protrude at its ends, or alternatively each mandrel may comprise merely two short stub shafts, arranged at such spacing as to overlap the edges of the web being wound so that, in the finished paper roll, said stub shafts are partly inserted in the ends ofthe roll.

We claim:

1. A paper winder comprising first and second winder drums arranged in coacting relationship to form a first nip, a third winder drum arranged in coacting relationship with said second winder drum to form a second nip, first and second mandrels, supports for said first and second mandrels arranged to permit said first and second mandrels to move away from and towards said first and second nips respectively, and means for urging said first and second mandrels towards said first and second nips respectively, the disposition of said winder drums and said mandrels being such that a first width ofa split web may be fed between said first and second winder drums to said first mandrel for winding thereon while a second width of said split web is being simultaneously fed between said second and third winder drums to said second mandrel for winding thereon.

2. A winder as defined in claim 1, including pivoted mountings for said first and third winder drums so that said first and third winder drums may be swung away from the first and second mandrels respectively after the roll of paper on the respective mandrel has been wound to a predetermined diameter so that thereafter each of the two rolls then only bears against the second winder drum.

3. A winder as claimed in claim 2, in which the second winder drum has a larger diameter than the first and third winder drums.

4. A winder as claimed in claim 1, in which the three winder drums are substantially in line with one another.

5. A winder as claimed in claim 1, including first and second carriages for supporting said first and second mandrels respectively, first and second tracks for said first and second carriages respectively, said tracks being so disposed that movements of said carriages along said tracks cause the respective mandrels to move towards and away from the first and second nips, and means drivingly connected to each of said carriages for urging the carriage towards the respective nip.

6. A winder as claimed in claim 5, in which the means to urge each carriage towards the respective nip comprises a pivotal arm, a fixed pivot at one end of said arm, the other end thereof being connected to the carriage, and a ram arranged to move the arm about its pivoted end.

7, A winder as claimed in claim 5, including a first toothed member carried by the carriage, a second toothed member carried by a fixed support and meshing with said first toothed member, the two toothed members being movable to cause the carriage to be driven towards or away from the respective nip.

8. A winder as claimed in claim 7, in which one of the toothed members is a toothed rack and the other toothed member is a pinion, and further including a motor operable to rotate said pinion.

9. A winder as defined in claim 5, including a first toothed rack formed on the carriage, a fixed support, a second toothed rack secured to said fixed support, and a pinion located between said racks and meshing with both ofthem.

10. A winder as claimed in claim 9, including a hydraulic ram, said pinion being mounted on the end of said ram so as to be moved along said second toothed rack by energization of said ram.

11. A winder as claimed in claim 7, including a toothed rack carried by the carriage and a plurality of driven gears located along the track, in which said toothed rack is engageable in turn by each of said gears so that the toothed rack and hence the carriage can be driven from each gear to the next adjacent gear in succession to move the carriage towards or away from the nip.

12. A winder as claimed in claim 5, including driving means for said carriage comprising an endless band to one run of which the carriage is secured, so that movement of said band in one or the other direction causes the carriage to move towards or away from the nip.

13. A winder as claimed in claim 5, in which the track is pivotally mounted so as to permit a roll of paper being wound to be urged towards the drums so as to engage two of the drums or only one ofthe drums as desired.

14. A winder as claimed in claim 13, including a pivotallymountcd frame carrying the track and a hydraulic ram operable to produce pivotal movement of said frame. 

1. A paper winder comprising first and second winder drums arranged in coacting relationship to form a first nip, a third winder drum arranged in coacting relationship with said second winder drum to form a second nip, first and second mandrels, supports for said first and second mandrels arranged to permit said first and second mandrels to move away from and towards said first and second nips respectively, and means for urging said first and second mandrels towards said first and second nips respectively, the disposition of said winder drums and said mandrels being such that a first width of a split web may be fed between said first and second winder drums to said first mandrel for winding thereon while a second width of said split web is being simultaneously fed between said second and third winder drums to said second mandrel for winding thereon.
 2. A winder as defined in claim 1, including pivoted mountings for said first and third winder drums so that said first and third winder drums may be swung away from the first and second mandrels respectively after the roll of paper on the respective mandrel has been wound to a predetermined diameter so that thereafter each of the two rolls then only bears against the second winder drum.
 3. A winder as claimed in claim 2, in which the second winder drum has a larger diameter than the first and third winder drums.
 4. A winder as claimed in claim 1, in which the three winder drums are substantially in line with one another.
 5. A winder as claimed in claim 1, including first and second carriages for supporting said first and second mandrels respectively, first and second tracks for said first and second carriages respectively, said tracks being so disposed that movements of said carriages along said tracks cause the respective mandrels to move towards and away from the first and second nips, and means drivingly connected to each of said carriages for urging the carriage towards the respective nip.
 6. A winder as claimed in claim 5, in which the means to urge each carriage towards the respective nip comprises a pivotal arm, a fixed pivot at one end of said arm, the other end thereof being connected to the carriage, and a ram arranged to move the arm about its pivoted end.
 7. A winder as claimed in claim 5, including a first toothed member carried by the carriage, a second toothed member carried by a fixed support and meshing with said first toothed member, the two toothed members being movable to cause the carriage to be driven towards or away from the respective nip.
 8. A winder as claimed in claim 7, in which one of the toothed members is a toothed rack and the other toothed member is a pinion, and further including a motor operable to rotate said pinion.
 9. A winder as defined in claim 5, including a first toothed rack formed on the carriage, a fixed support, a second toothed rack secured to said fixed support, and a pinion located between said racks and meshing with both of them.
 10. A winder as claimed in claim 9, including a hydraulic ram, said pinion being mounted on the end of said ram so as to be moved along said second toothed rack by energization of said ram.
 11. A winder as claimed in claim 7, including a toothed rack carried by the carriage and a plurality of driven gears located along the track, in which said toothed rack is engageable in turn by each of said gears so that the toothed rack and hence the carriage can be driven from each gear to the next adjacent gear in succession to move the carriage towards or away from the nip.
 12. A winder as claimed in claim 5, including driving means for said carriage comprising an endless band to one run of which the carriage is secured, so that movement of said band in one or the other direction causes the carriage to move towards or away from the nip.
 13. A winder as claimed in claim 5, in which the track is pivotally mounted so as to permit a roll of paper being wound to be urged towards the drums so as to engage two of the drums or only one of the drums as desired.
 14. A winder as claimed in claim 13, including a pivotally-mounted frame carrying the track and a hydraulic ram operable to produce pivotal movement of said frame. 